In general, an optical sensor is known which detects movement of a detection object such as a finger or a hand by using a light emitting element and a light receiving element (see, e.g., Patent Documents 1 to 3). The optical sensor described in Patent Document 1 is provided with nine light emitting elements surrounding one light receiving element, and identifies a light emitting element from which reflected light from the detection object occurs, out of the nine light emitting elements, thereby detecting movement of a detection object. The optical sensor described in Patent Document 2 is provided with a plurality of pairs of light emitting elements and light receiving elements. In the optical sensor, light from the light emitting elements are reflected by a mirror provided within the sensor and a detection object, and movement of the detection object is detected by using a Doppler shift of these two reflected lights. The optical sensor described in Patent Document 3 is provided with three light emitting elements surrounding one light receiving element. In the optical sensor, reflected light from a detection object is received for each of the three light emitting elements, and movement of the detection object is detected on the basis of the phase differences among the three reflected light.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-188087    Patent Document 2: Japanese Patent No. 4094424    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2011-227574